Tempting as it may be for a man to tell his partner everything, a history of sleeping with prostitutes is one little detail he might consider keeping to himself.

All new relationships are a trade-off between secrecy and intimacy, a reckoning between what a partner needs to know and what he probably shouldn’t. While a single woman’s best-kept secret is the number of men she has slept with, for some single men it’s the number of times they’ve paid for sex. With erotic massages, dominatrixes, and escorts just a phone call or mouse click away, there’s a good chance that an eligible New York bachelor over 30 has paid for sex of some sort at least once in his life. For the most part, guys don’t talk about it. But when relationships get intimate, some do, causing their girlfriends and wives to hit the roof. In a city where women flaunt their rocks and trade on their sexuality every day, the have-you-paid-for-sex conversation remains a relationship deal-breaker, whether or not it should.

“Every guy I know has been with a prostitute,” says my friend David, 46, an actor and writer who solicited quite a few before he was married.

“If we lived in a society where everyone got all the love and sex they wanted, there probably wouldn’t be as many. But guys don’t get all the sex they want.” At various points in his life when he’s wanted to be honest about who he is, he has opened up to women about his john past. Though some were curious, many “were horrified,” he says. “They took the position that anyone who would pay a woman to have sex is just a horrible man who treats women with no respect and reduces them to objects. I quickly ended those relationships.”

But don’t those women have a point? He says no: “The assumption that an encounter with a prostitute defines a man, his sexuality, and his character is a leftover from Puritan times. In any line of work, there are different kinds of transactions. Not every woman who gets paid to have sex is being forced, and not every man who pays for it is sexist.”

Heather, 30, a music-industry executive, dated a 26-year-old guy last summer who told her he had been soliciting prostitutes since he was 22. She stopped seeing him soon after. “We were on a camping trip in a tent in New Jersey, talking a lot, and he asked me how long it had been since I had had sex. I told him it had been more than several months, and when I asked him, he got a weird look on his face and said, ‘I get sex when I need it. You know that movie Pretty Woman? I’m kind of like Richard Gere.’ ”

Her first concern was disease; though he told her he always used protection, it did little to comfort her. But beyond that, she couldn’t make sense of his need for it: “This was a young, good-looking lawyer who could go into any bar and pretty easily get a woman to go home with him. So why would he pay for it if it wasn’t his only way of getting sex?”

“He got a weird look on his face and said, ‘I get sex when I need it. you know the movie Pretty Woman? I’m kind of like Richard Gere.’ ”

Ask a man and he’ll supply any number of answers—he doesn’t want to go to the trouble of a bar pickup, he wants to fulfill a particular fantasy, he doesn’t want to have to worry about his partner’s pleasure—but most women have a tough time understanding this way of thinking.

Tracy Quan, author of The Diary of a Manhattan Call Girl and a former call girl herself, suggests that some men are “born johns,” who because of childhood relationships or some X-factor start trolling young and keep it up. Others “want to have sex in the middle of the day at the drop of a hat without any preliminaries.” Although most of her clients were married men who had been rejected by their wives or sexually naïve men who wanted experience, some were single, and not all were bad in bed.

“I had a noticeable number of clients who were attractive and sexually skilled to the point where I would wish they were less so,” she says. “I had good-looking guys who knew where my clitoris was. I came from time to time.”

Even johns themselves are divided when it comes to making sense of their actions: Some feel no shame, while others remain haunted by their experiences. “When I first came to New York, I was 25 and living up on 98th Street,” says Bob, 47, a photographer. “I would pick these girls up and bring them to my place, and before we had sex, we would just lie in bed. I knew that the girl wasn’t going to judge me and that she was fun. I learned how to relax around women.”

On the other end of the spectrum is Tim, 47, a writer, who confessed to his now-wife that he used to see street hookers regularly. She cried and he went to therapy. “It exposed a part of me that she didn’t know about,” he says. “I had a separate need for power and control that didn’t have to do with sex.” He thinks men who go to hookers are victimizing women whether they admit it or not: “I understand women’s disgust and completely share it. It has a degrading aspect for both people involved.”

In the case of the Richard Gere guy, Heather concluded that what he had done had affected his ability to be intimate with women. He had trouble kissing her, and though he said he wouldn’t go to another prostitute if they got serious, she wasn’t sure she believed him.

In the end, a john past may fall into the category of things best left unsaid. “Women could learn a lot from watching the way guys function,” says Quan. “Men know instinctively, I am what I am and there’s no way every woman would accept every inch of me. I think women should accept the idea of compartmentalization in men and compartmentalize more of themselves.”

Bob, for his part, has chosen discretion: “I don’t tell my wife, and part of it is to protect her. I don’t think a woman is capable of understanding it even if I were given the chance to explain. A guy doesn’t want to show 100 percent of himself. He wants to show 99 percent.”